The accounts of how police came to fire more than a dozen bullets into the armored U.S. embassy vehicle with diplomatic plates are still vague. Two U.S. embassy employees and a Mexican Navy captain were traveling in the Toyota Landcruiser near Cuernavaca, south of Mexico City, when they came under attack by gunmen who included federal police. Weissenstein reports that "the Mexican government said federal police were conducting unspecified law-enforcement activities in the rural, mountainous area known for criminal activity when they came upon the car, which attempted to flee and came under fire from gunmen in four vehicles including federal police." As The New York Times' Randal C. Archibold notes, "Mexican newspapers have reported that all of the shots fired came from the police." CNN carried a bit more detail from an official Mexican Navy report:

When a vehicle containing Federal Police approached and its occupants brandished their weapons, the driver of the diplomatic vehicle tried to evade them and return to the main highway. At that point, the police sprayed bullets into the black SUV with diplomatic plates.

Moments later, three other vehicles carrying Federal Police joined the attack, also shooting at the U.S. Embassy vehicle.

Mexican authorities still haven't said whether they think this was a mistake by police or a case of corrupt officers attacking a U.S. vehicle on purpose, but while they sort out what happened, the detention of the 12 officers has caused a scandal of its own: Protesters say the officers are being held unjustly for doing their jobs, and that their lawyers are being kept from them, Archibold reports. Authorities still haven't decided whether to prosecute the officers.

News reports are focusing on the Germanwings pilot's possible depression, following a familiar script in the wake of mass killings. But the evidence shows violence is extremely rare among the mentally ill.